Conventionally, there has been proposed a spark plug which has a ground electrode into which a noble metal tip is embedded such that the noble metal tip projects from the distal end of the base member of the ground electrode. The noble metal tip is joined to the base member of the ground electrode by means of resistance welding. Noble metal tips used for the electrodes of such a spark plug are formed of a noble metal which is more excellent than the electrode base member in terms of durability against spark discharge and oxidation (e.g., platinum, iridium, ruthenium, rhodium, etc.) or an alloy containing such a noble metal as a main component.